One method of improving the lifetime of electronic devices and circuits, especially in harsh environments, is to seal them inside a package. When the package is designed so that the rate of leakage of certain molecules into the package is less than a certain very low rate, the package is said to be hermetically sealed.
Many methods of producing hermetically sealed packages are known. A very common method involves the use very high quality welds which have inherently low leak rates. In practice however, a sufficiently large number of such welds require rewelding due to high leak rates that the overall cost of the process is high. Several methods of sealing involving spraying, brushing or dipping with a liquid material which is subsequently cured are also known. However, applying these methods to the improvement of an existing weld requires the maintenance of a pressure differential to impregnate the weld and does not result in as low a leak rate as might be desired. In addition, prior art methods often require high temperatures and/or harsh curing compounds which may damage electronic components within the package.